Air Purifiers as White Noise Machines (jefftk.com)
senderista 13 hours ago
simonbuilds 12 hours ago
kazinator 9 hours ago
rootusrootus 8 hours ago
eli 8 hours ago
olyjohn 8 hours ago
cosmic_cheese 8 hours ago
I’d never put two and two together until now, but that fan had to have been a major factor in some of the unexpectedly great naps in that room.
dylan604 5 hours ago
dylan604 5 hours ago
arjie 12 hours ago
PM2.5: 2.6 µg/m³
PM10: 0.5 µg/m³
VOC index: ~97
CO₂: ~505 ppm
That's the baseline. When we're cooking, like now, it's: PM2.5: 10.8 µg/m³ (AQI ~46)
PM10: 17.5 µg/m³
VOC index: 122
CO₂: 572 ppm
None of those seem particularly concerning. We have a gas range, and 15 min past the end of cooking everything is fine. I must imagine that most people don't live right next to the freeway so they probably have even better air quality except during wildfire season.gpm 11 hours ago
PM2.5 - My impression is the health risks here are more cumulative exposure (and include things I'd like to go without in my life, like alzheimers) and a pretty straight line of "lower is better all the way to zero". The WHO's guideline is mean exposure of 5 µg/m³ so I guess I'd adopt that if I had to put a number on it. (But it's a mean, I wouldn't worry about briefly exceeding it)
PM10 - No real opinion (I'd rather worry about PM2.5)
VOC index - I'm not sure this is a standardized thing, but the version I've come across is an index relative to the average that particular sensor has seen in the last 24 hours. So there's no standard possible here.
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As for a gas range I would worry about NOX considering the studies with them causing and aggravating asthma. That said your CO2 levels are low so I suspect you might have sufficient ventilation that this isn't a huge issue for you (especially if that ventilation is in the form of a fume hood over your stove that you actually use).
teravor 9 hours ago
CO2 is usually a proxy for air quality because outside is usually something consistent like 400 therefore deviation from that figure indicates staleness.
gpm 8 hours ago
Besides which, proxy or directly high CO2 means you should ventilate...
phyzome 5 hours ago
teravor 5 hours ago
having said that, it's possible they omitted what other gasses and %s they used for advantage. there could be some mitigation possible there.
eastbound 38 minutes ago
pythonsnake 25 minutes ago
amluto 8 hours ago
I target 0 PM2.5, but this only necessarily makes sense as a target if you have the ability to filter your home's supply air. And a good vent hood should be able to avoid any detectable bump while cooking (although a vent hood without filtered makeup air may cause a bump due to increased infiltration of exterior air).
idiotsecant 8 hours ago
amluto 7 hours ago
The instrument is pretty crappy - it has basically no calibration or, AIUI, long term stability. So you can’t really use it to characterize the chemical content of the air. What you can do is observe changes. I’m guessing the manufacturer wanted to avoid people getting confused by the absurd raw reasons, so they came up with a formula called “VOC Index” that HPFs the data. It will average 100 IIRC. You’re supposed to use it to notice events that cause changes - if it hits 170 every day at 2 PM them you can guess that something’s happening at 2 PM.
None of this is in the chip. It’s implemented by the driver. There’s an implementation in esphome, for example.
GeoAtreides 3 hours ago
dgacmu 8 hours ago
CO2 while occupied is generally under 750; I'd prefer to keep it under 700 but we also balance that with energy efficiency for that make-up air; I don't have an ERV, so we suffer a little there.
(We don't live by a freeway but - (a) Pittsburgh's air isn't great; and (b) the canadian wildfires were pretty bad here at times this summer, and that was what caused that 0.8 ug/m^3 pm2.5 spike).
We have, um, a lot of air filters left over from covid, though, so we're a little spoiled in terms of being able to manage AQI easily.
jefftk 8 hours ago
(Equivalent to saying you have more people under 2.5 years old than under 10 years old.)
kj4211cash 7 hours ago
gopalv 14 hours ago
I got one during Santa Cruz wildfires in 2020 and now the kids have a pavlovian reflex to sleep once that gets turned on.
Ikea makes an air-purifier table, which is a end-run around it being a useless box in the room when switched off.
It's fairly expensive, not as good as a purpose built one, but it blends into the average room pretty well.
LordFast 9 hours ago
It might not be guaranteed to help, but it sure doesn't hurt since it's cleaning the air anyway.
otterdude 7 hours ago
I have one blowing gently across my face while I sleep. It cools me down, and blocks out the highway noise.
kakacik an hour ago
tgv 34 minutes ago
But, if I'm not mistaken, the damage you speak of is caused by disrupting sleep. So the idea is that if a white noise generator can drown out the interruptions, it helps you sleep better. There are studies that say noise doesn't help, and there are those that say it does. And it's all real-life medical research, so pretty unreliable. I found one controlled study (https://doi.org/10.1093/sleep/zsag001), but it's small, and only 7 days, and it's in a lab, so not guaranteed to translate to normal conditions either.
And don't ignore the placebo effect. Perhaps believing that pink noise helps is sufficient for some.
Perhaps a better recommendation is good ear plugs.
JohnBooty 11 hours ago
For most circumstances where someone would use
a white noise machine, this kind of small purifier
is all-around better.
Hmm. The word "most" is doing a lot of work here.Depends if you enjoy fresh air when you sleep or not. If you've ever monitored CO2 levels you know how quickly they climb in a closed room.
But, if you are blowing fresh air into a room, or have the windows open, the filtration effectiveness of these units approaches zero pretty rapidly. And these air purifiers aren't exactly free to run: they use ~50-100W of power and if you run them 24/7 you can expect to spend $100+ per year on filters.
So there's no perfect answer...
manwe150 8 hours ago
jefftk 8 hours ago
That sounds too high? An AirFanta 3Pro on "2" is 141 CFM at under 5W https://www.jefftk.com/p/running-an-air-purifier-on-batterie...
dekhn 14 hours ago
mfkp 13 hours ago
LTL_FTC 13 hours ago
jerlam 13 hours ago
kube-system 13 hours ago
schiffern 13 hours ago
>Of course, the problem with this is you are just spending more money on filters, which is the expensive part.
For up-front cost, this is true.For cost over time, twice the filters means twice the replacement interval, so the additional filter cost cancels out.
kube-system 10 hours ago
I'm sure it works but like any engineering decision it has pros and cons.
schiffern 9 hours ago
>you get to look at any collected dirt
If that's your biggest worry in life, seems like a high-class problem! Many people are satisfied 'just' protecting their heart and lung health.However, if you really don't want to look at it, you can always flip most DIY designs inside-out so the fans blow in and dust collects on the inside instead of the outside! This doesn't clean the room quite as efficiently, but if the appearance of dust is a major concern that should be a fix.
kube-system 8 hours ago
Flipping the fans isn’t great because then you have to clean the fans, this is why draw-through is the standard configuration. Also many designs like this rely on negative pressure to seal properly or even stay together. You might just have the lid take off like a helicopter.
jefftk 8 hours ago
jerlam 11 hours ago
All the purifier companies realized they make more money selling overpriced filters, so $60+ for the OEM filters is common nowadays. Despite it just being a standard HEPA filter cut to a specific size.
Airfanta 3 Pro filters (four) - $57
Coway Mighty Filter - $60
Coway Mighty2 Filter - $70-$80
I'd be concerned about the availability of filters after a few years. Some of these companies have been changing their models and filter type every year to add some nebulous feature. Others just go out of business.
kube-system 10 hours ago
HEPA media itself is a commodity and aftermarket filters (and the BOM cost to the OEM) tend to level out at whatever rate is minimally profitable per area of filter media.
The upfront cost of this device is high for what you get, because you're mostly buying filter media. The device itself is not much of a polished product. I'm sure it works fine but I wouldn't want one in my living room.
jefftk 8 hours ago
I leave them on setting 2 (unless someone is sick or we're having a lot of people over), and we get ~425 CFM for about $40/y in power (~5W each).
Nukit 2 hours ago
schiffern 13 hours ago
The trick is to use high-airflow MERV 13 filters (ideally 3M 1900, which has high pleat count and low resistance) instead of high-resistance HEPA filters, so axial PC fans can generate enough pressure.
bradknowles 12 hours ago
gpm 12 hours ago
For a standalone air filter which is pushing the filtered air into the same room its drawing from, we can assume reasonably good mixing of the intake and exhaust air. Thus to be equivalent to a HEPA-filter it only needs 1/3rd more airflow... Which really isn't much.
This doesn't follow for a a fancier setup where you're taking dirty air and blowing it into a cleanroom or something... but that's not how we're typically using household air filters.
CoffeeOnWrite 9 hours ago
schiffern 8 hours ago
mattlondon 12 hours ago
mfkp 12 hours ago
daniel_iversen 8 hours ago
idiotsecant 8 hours ago
There might be some to your dog, on the other hand. Anecdotal, but my dog went deaf pretty early and he sleeps in a room where I run an air purifier all night. Not sure if there is correlation or causation there but that's my little anecdata.
pestatije 7 hours ago
settsu 12 hours ago
I grasp that such an approach might draw unfiltered surrounding air along with the filtered stream of air, and imagine that it would likely be easily overwhelmed by a steady supply of exceptionally polluted air (wildfire smoke or simply a heavily polluted urban area), but I still would be interested in knowing if the compromise never overcomes a level of placebo effect, or if there's a point where it actually achieves measurable benefit (both in efficacy and portability—like a even more compact and directional version of the Corsi-Rosenthal computer fan solution.)
JohnBooty 11 hours ago
These directed-air "personal models" make a lot of sense to me... at least in theory. I haven't seen them properly tested.
The big air purifiers work great.. if the room is closed up. But their effectiveness approaches zero if you have the windows open or otherwise have unfiltered air entering the room. Which is kind of important, if you don't enjoy breathing in sky high levels of CO2. (If one's allergies are bad enough, or a wildfire is raging outside, CO2 might of course be preferable to particulates)
jerlam 9 hours ago
https://air-fanta.com/products/airfanta-4lite
However, testing seems to show that the clean air flow is neither wide nor far; it would only be effective right next to your face and you can't really move:
https://www.reddit.com/r/Masks4All/comments/1di1n4t/can_a_po...
There aren't a lot of use cases for it.
jefftk 8 hours ago
rob-olmos 14 hours ago
TedDoesntTalk 14 hours ago
kccqzy 13 hours ago
jerlam 13 hours ago
bradknowles 12 hours ago
Where I need extra help is with VOCs in certain locations. Like, in or near bathrooms. Or the cat litter boxes. IQAir does sell their GC line for that, and we have a couple of those. But the activated carbon filter media is super expensive. And these things are huge. Like, bigger than a dorm refrigerator.
So, I welcome an alternative that does VOCs well.
TedDoesntTalk 11 hours ago
kccqzy 10 hours ago
ungreased0675 8 hours ago
benbojangles 7 hours ago
bob1029 7 hours ago
brokensegue 13 hours ago
paimapi 12 hours ago
brokensegue 11 hours ago
jefftk 7 hours ago
rootusrootus 8 hours ago
snarfy 7 hours ago
amelius 12 hours ago
npongratz 12 hours ago
turtlebits 13 hours ago
I prefer having quiet air filters that I can run all day (based on air quality) instead of noisy ones I only use at night.
kube-system 13 hours ago
alistairSH 13 hours ago
I have one in the bedroom. On low, I barely hear it during the day (extra ambient noise from outside) but at night the white-noise is subtle but effective. That said, I don't like "loud" white noise, just a quiet hum.
schiffern 12 hours ago
Housefresh, which is a criminally underrated review channel btw, recently did a comparison of PC fans for this purpose. The Thermalright TL-14C family came out strong in the "Silent" category, with the best ultra-quiet 24/7 fan speed performance. This comes at the cost of slightly worse max speed CADR vs the venerable Arctic P14.
bradknowles 12 hours ago
I still haven’t seen anything else that can compare to IQAir HyperHEPA filters. They use these things in hospitals.
turtlebits 12 hours ago
Turning them up to med/high would just cause too much airflow.
jefftk 8 hours ago
I agree big fans moving slowly is better all else equal, and something AirFanta-like that used a 12" fan could be even better.
mistic92 11 hours ago
wolvoleo 12 hours ago
For sleeping I prefer rain sounds though
jsLavaGoat 12 hours ago
Terr_ 3 hours ago
johnea 9 hours ago
I like silence.
I consider noise from things like a refrigerator, or a computer case fan, to be distracting, and a reduction in the quality of my environment.
White noise is still noise, and there's no noise like no noise...
JoshTriplett 8 hours ago
fwlr 4 hours ago
gnabgib 4 hours ago
The naming isn't great in the competition, but: Alpine, EarGasm, EarPeace, Loops are significantly better. Recent Alpine reviews suggest a material change - so maybe not them (haven't tried the new ones). They all come in different editions which is mostly about which frequencies they block/allow through.. loop is trying to push the price boundary (probably avoid, especially their "active" line).
All better than basic fluorescent foam earplugs though, easier to use and better sound blocking (the good audio ones allow you to speak/hear voices at close to normal volume in front of a 90dB sound stage)
diogenescynic 6 hours ago
alephnerd 12 hours ago
encom 14 hours ago
>removes smoke and infectious particles
Where do people live that they need to remove such things, 18th century London?
yodon 14 hours ago
SF Bay Area during the summer fires of a few years ago
grandpajoey 14 hours ago
encom 12 hours ago
grandpajoey 12 hours ago
encom an hour ago
fwip 12 hours ago
rootusrootus 8 hours ago
helterskelter2 13 hours ago
jerlam 13 hours ago
Wind blows smoke around. There are currently fires in northern Michigan that are affecting the air quality in Chicago, which is 350+ miles away.
fellowniusmonk 13 hours ago
My allergies became generally better at all hours just from sleeping in super cleaned air.
Why? Reducing baseline inflammation perhapse? Maybe decreased inflammation during sleep helps too, improved breathing? idk. Whatever it is this organism seems to prefer it.
Even when exposed to allergens during the day the run up to sneezing is much slower or doesn't happen.
yread 13 hours ago
alnwlsn 12 hours ago
https://commons.wikimedia.org/wiki/File:Wildfire_smoke_Wyand...
It just looks like fog, but it is smoke, and the sky has an unusual orange color. Smells and tastes like you are standing in the path of a campfire, but you can't move out of the way. It irritates your eyes and throat if you spend more than 20 mins out there. You can go inside, but if the building you are in is leaky, it will smell like smoke inside there too.
The actual fire was hundreds of miles away. You can try driving in any direction for hours and not be clear of the smoke. Still, compared to other areas, this is barely worth complaining about.
tredre3 12 hours ago
weird-eye-issue 9 hours ago
gib444 36 minutes ago